Effective dose 50 of desflurane for laryngeal mask airway removal in anaesthetized children in cataract surgeries with subtenon block

BACKGROUND: Quantification of the depth of desflurane anesthesia required for laryngeal mask airway (LMA) removal in children has been done with the use of intravenous fentanyl or caudal anesthesia. This study aimed to determine the end-tidal concentration of desflurane required for LMA removal in children without the use of caudal or opioid analgesia in children undergoing elective cataract surgery. MATERIALS AND METHODS: Our study enrolled 25 American Society of Anesthesiologists I and II children aged 2-10 years, undergoing elective cataract surgery. Anesthesia was induced with sevoflurane and oxygen/nitrous oxide using face mask and a size 2 LMA inserted. A subtenon block was administered in all children before surgical incision. Desflurane was used for maintenance of anesthesia. Predetermined end tidal concentration of desflurane was maintained for 10 min at the end of surgery before LMA removal was attempted. End tidal concentrations were increased/decreased using the Dixon up-down method (with 0.5% as a step size) in the next patient depending on the previous patient's response. Patient responses to LMA removal were classified as “movement” or “no movement.” RESULTS: 50% effective dose (ED(50)) for successful removal of the LMA with desflurane in the presence of subtenon block was 3.6% (3.20-3.97%) and that the 95% ED(95) was 4.648% (4.15-6.47%). CONCLUSION: Laryngeal mask airway removal can be successfully accomplished in 50% and 95% anesthetized children at 3.6% and 4.65% end-tidal desflurane concentration.